Electrical condenser



Se t. 29, 1925. 1,555,251

w. H. PRIESS ELECTR I CAL CONDENSER Filed Juno 5. 1921 gte st: ess InMentor:

41w Atty Patented Sept. 29, 1925.

UNITED STATES PATENT OFFICE.

WILLIAM H. rnrnss, or iannnonnnnssacnusn'rrs, nssisnon 'ro WIRELESS SPE-CIALTY APPARATUS COMPANY, or BOSTON, MASSACHUSETTS, A UORPORATION or NEWYORK.

ELECTRICAL CONDENSER.

' a citizen of the United States of America,

and a resident of Belmont, State of Massa:

chusetts, have invented certain new'and useful Electrical Condensers,the principles of which are set forth in the following specification andaccompanying drawing, which disclose the form'of the invention which Inow consider to be the best of the various forms in which the principlesof the invention may be embodied.

This invention relates to electrical condensers and especially to thetype adapted for use in radio transmitters.

The specific embodiment of the invention herein illustrated is acondenser especially adapted for use in pack sets; that is, compactradio transmitting and receiving sets extensively used by the Army andNavy for field, landing and other work. Such condensers have a capacityof .004 M. F. and are able to withstand a voltage of about 16,000 voltsat six amperesat a wave-length of 600 meters.

The condenser of the type herein illustrated'consists of a stackcomprising several sections connected in series in order that therequired potential may be withstood, and each section comprisesalternate sheets of a suitable foil, such as lead foil, and dielectric,such as mica. The most satisfactory use of such condensers is underconditions in which the sheets of foiland dielectric are in intimatecontact, as more fully" described and discussed in my co-pendinapplication Serial Number 456,903,v file March 30, 1921, that is, inwhich all air and moisture has been excluded and removed -from betweenthe sheets and also from which all impregnating or insulating waxes oriiuids, or as much as possible, which may have been used during theprocess of building the stack are removed.

An object of the present invention is to provide a compact, cheapcondenser adapted for eficient service.

Another object of the invention is to maintain the intimate contactbetween the sheets of foil and dielectric in service.

Another object of the invention is to provide a condenser in which theclamping means is independent of the casing in which such stack andclamping means is suitably secured.

In the accompanying drawings, I have illustrated one embodiment ofthe'invention' in which Figure 1 is a plan View of the condenser withportions of the cover broken away;

Fig. 2 is a vertical sectionon the line 22 ofl ig. 1 looking in thedirection-0t the arrows;

Fig. 3 is an elevation of the condenser witih a portion of the casingbroken away; an

Fig. 4 is a detailed perspective-view of a spring pressure plate used inthe construction of the condenser.

As herein illustrated, the stack S comprises a number of sections 1connected in series at 2, mica separators 3 being interposed between thesections and extending beyond the connections to insulate the successlveconnections at opposite sides from each other. The stack at one end isprovided with a copper lead 4i which is electrically connected to ametal casing 5, the easin'g constituting one terminal of the condenser,and the opposite end section is provided with a copper lead 0electrically connected to a terminal 7 extending through an insulatingcover preferably of bakelite dilecto, secured to the casing 5 by meansof the screws 9. lhis stack S consists of alternate sheets of foil anddielectric as above described,and may be built and constructed by themethod described in the above-mentioned application, whereby all air,moisture and insulating material are can eluded from between thesuccessive sheets of the stack.

' in order tom have provided I i is independent, .uljflplil j 1 ture isconcerned, of the casing 5 and also of the cover 8. The clamping meanscomprises also an insulating block or member 10 at that end of the stackwhich is connected to the terminal 7; and also a spring plate 11 at theopposite end of the stack. Metal end tastings or pressure members 12 arearranged on the outside of the members 10 and 11, these castingsextending over the entire active surface of .the foil and dielectric anda substantial distance beyond the edges of the foil as illustrated inFigs. 1 and 2. The members 12 are preferably of cast steel, and areconnected together by a pair of metal bolts 13, one bolt being locatedat each side of the condenser and centrally oi the plates whereby uponthe tightening of the bolts, uniform pressure is exerted over the opposite ends of the stack. These bolts are sufficiently spacec. from thesides of the stack to prevent brushing or discharge between the same andthe stack. In assembling the condenser, the end plates 12 with the stackand plates 10 and 11 between them are preferably placed in an arborpress or C clamp and pressure is applied until the plate 11 is flat. Thebolts are then tightened to maintain this pressure. The plate 11constitutes a spring plate which is normally bowed, as illustrated inFig. 4e, and may consist of any suitable spring material such asvanadium steel. Upon the tightening of the bolts 18, uniform resilientspring pressure is exerted upon the opposite ends of the stack tomaintain the sheets in intimate contact, and any temperature changesresulting in varying length of the stack in service is compensated foror allowed by the spring 11. Upon the contraction of the stack, thespring follows up the contraction to maintain the pressure constant.

As more clearly illustrated in Fig. 3, the lower portion 1 1 of thecasing 5 is reduced in size, forming shelves or ledges 15 at oppositesides thereof against which engage portions of the end pressure members12 ex tending beyond opposite sides of the stack. These clamping endplates or members 12 also have reduced portions at 16 which extend intothe reduced portion 14 of the casing, providing space 1(3 between thestack S and the casing whereby the stack, although resting on thecasing, is suitably spaced and insulated from the metal parts thereof,with correspondingly reduced volume and weight of insulating filler inspace W (Fig. 2).

In the construction herein illustrated, the sheets of foil anddielectric are arranged vertically within the casing 6 at right anglesto the cover 8. Hence insulating block 10 (Fig. 2) and adjacentclamp-portion C space the high potential end of the stack away from theadjacent side wall of metal casing 5; and high potential lead (3, at thepoint of connection with the high potential terminal-section of thestack is-looated close to the casingopening and insulating cover 8 outthrough which said lead extends. At opposite sides of the bolts 13 areupwardly-projecting fingers 17 which are engaged at their upper ends 18by the cover 8 to maintain the clamp and the stack in positidn withinthe casing. The condenser, herein illustrated may be secured to anysuitable frame 19 by means of screws 20 extending through the frame andinto lugs 21 formed on the casing 5.

After the condenser stack and its clamp have been placed within thecasing and be fore the cover 8 has been secured in place, space llwithin the casing 5 around the stack and clamp may be filled with anysuitable insulating and embedding material such as paraffin. Thisembedment may be formed by the methods and by the means described in theapplication above-mentioned. This forms a compact, holosteric embednientwithin the casing 5 and around the stack, thoroughly insulating thestack in the casing. Fish paper sheets 22 may be interposed between thecasing 5 and the ends of the clamp.

It is to be understood that the invention is not limited to theembodiments and features specifically shown and described herein, butthat such embodiments and features are subject to changes andmodifications without any departure from the spirit of the invention.

I claim 1. In an electrical condenser, a stack of sections connected inseries and having its opposite ends at a difference of potential, aspring plate at one end of the stack, an insulating member at the otherend of the stack, and an allmetal clamp enclosing said stack, springplate and insulating member whereby resilient spring pressure ismaintained upon the stack.

2. In an electrical condenser, a stack of conducting and dielectricsheets constructed to have a high potential difference between its endsin service; a metal casing for said stack having a cover of insulatingmaterial, the stack being located parallel to said cover with its sidesspaced from the walls of the metal casing; an all-metal clamp extendingfrom end to end of the stack, constructed to maintain the sheets fromend to end of the stack under a high compression, the ends of said clampextending parallel with opposite walls of the metal casing and locatedentirely within the casing; an insulating plate between and parallel toone end of the stack and the adjacent end of said all-meta clamp; aspring plate tending to bend but'located -for more or less flatteningduring service between and parallel to the other end of the stack andthe a-ljacent end of said all-metal clamp; and means for securing theclamp in fixed position within the casing.

3. In an electrical condenser, a stack of lit) conducting and dielectricsheets constructed to have a high potential difference between its endsin service; a metal casing for said stack having a cover of insulatingmaterial; an all-metal clamp extending from end to end of the stack,constructed to maintain the sheets from end to end of the stack under ahigh compression during service, and located entirely within the casing;an insulating'block between and parallel to one end of the stack and theadjacent end of said all-metal clamp; a spring plate tending to bend butlocated to be more or less flattened during service betweenand parallelto the other end of the stack and the adjacent, end

- of said all-metal clamp; means for securing the clamp in fixedposition within the easing; a lead connecting one end of the stack withthe metal casing; and a condenser terminal extending through theinsulating casing-cover and connected to a lead extending from the otherelectrical end of the stack,

4Q In an electrical condenser, a stack of serially-connected sectionshaving its ends at a high potential difference corresponding with suchseries connection, each section comprising armature sheets andintervening dielectric; and the several sections having interveninginsulating separators; a metal casing enclosing said stack and having anopening for a circuit lead from the stack; a circuit lead extending fromone terminalsection of the stack out throughsaid casingopening; theother terminal-section of the stack belng electrically connected withsaid casing; an insulating member around said circuit lead and coveringsaid casing-opening; metal clamping means extending from end to end ofthe stack and over the ends thereof, with an intervening insulatingblock of substantially greater thickness than .said

insulating section-separators and located between said clamping meansand the terminalsection of the clam fro which said circuit lead extendsout o the sing, said insulating block being held under compression bysaid clamping means; andsaid stack being arranged in said casing withits armatures and dielectric sheets and said insulating block located atright angles to said insulating coverin r member and parallel to theside walls of sai casing, whereby said insulating block and adjacentpart of the clamping means lie between the end of the stack and a sidewall of the casing, and the side of the terminal-section of the stackwhich is adjacent to said insulating block is located near saidinsulating covering member.

5. In an electrical condenser, a stack of conducting and dielectricsheets constructed to have a high potentialdiiference between its endsin" service; a metal casing for said 7 stack having a cover ofinsulating material;

an all-metal clamp extending from end to end of the stack, constructedto maintain the sheets from end to end of the stack under a highcompression, and located entirely with in the casing; and aflatinsulating block and spring plate located parallel to the sheets inthe stack in positions in which they are held under compression with thestack by said clamp.

6. In an electrical condenser, a stack, a

clamp for said stack comprising end plates extending beyond the stack atopposite sides, means for holding the end plates compressed togetheragainst the ends of the stack, and a metal casin for said stack andclamp, a portion of said casing being of less width providing ledges atan intermediate portion thereof, said end plates having portions of lesswidth engaging said ledges, supporting the stack in spaced relation tothe casing, and with correspondingly reduced space between the stack andthe walls of the reduced portion of the casing.

7. In an electrical condenser, a stack, a clamp enclosing said stack, ametal casing provided with means upon opposite sides of the stack andengaging the clamp for supporting the stack within the casing, andspacing t e stack from the casing, and a cover upon said casing andco-operating with said clamp for securing the same in position withinthe casing.

; 8; In an electrical condenser, a stack of sections connected inseries, a clamp comprising end plates engaging the stack at oppositeends and extending over the active surfacethereof and latera ly beyondthe stack, bolting means connecting said end plates, a metal casinghaving an opening, enclosing said clamp and stack and coniprising areduced portion. forming ledges.

upon opposite sides, supporting the end plates, the stack being arrangedin spaced relation to said casing at all points, means electricallyconnecting one portion of said stack to the casing constituting aterminal, fingers upon said end plates extending toward. the open end ofthe casing, an insulating cover upon said casing engaging said fingersto hold the clamp and stack in positionwithin the casing, and a secondterminal connected to said stack and extending throulgh said insulatingcover.

9. 11 an electrical-condenser, aistack of sections connected in seriesand compris- 'ing alternate sheets of foil and dielectric,

haying an open end, enclosing said stack and clam and comprising areduced portion forming ledges upon opposite sides of the stack and enaging portions of the end fingers for holding the clamp and stack inplates spacing tie stack from the casing position within the casing, aterminal con 10 fingers upon opposite portions of the end nected to theopposite end of the stack and plates extending towards the open end ofextending through said insulating cover, the casing, means electricallyconnecting and an embedment of insulating material one end of the stackto the casing, the latwithin said casing surrounding said stack.

ter constituting aterminal, an insulating cover upon said casing andengaging said i p WILLIALI H, PRIESS.

